This invention relates to a revetment panel comprising a matrix of forms interconnected by cables and fabric, and a method of constructing in situ the revetment panel. The invention is used for erosion control or other purposes and is typically placed on embankments and other earthen structures below, at and above the waterline.
It has long been known to place erosion control structures along river and channel banks, shorelines and coastlines, and other places subject to erosion from hydraulic forces. Such structures have taken the form of, among other things, rip-rap, unconnected concrete blocks or slabs, and prefabricated blocks or other forms which must be transported to the installation site and there interconnected by cables or interlocking means and placed into position.
Also known is the technique of constructing erosion control structures in situ by filling the void between two laid-in-place interconnected fabric layers with a flowable filler material of sand or cementitious slurry. The filler material, which may be pumped into the void between such fabric layers either above or below the waterline, may later harden into a monolithic structure.
Several techniques have previously been used to control separation of fabric layers in previous in situ formed structures as filler material is pumped between the layers, and therefore to control the thickness of the hardened, monolithic structure. The two fabric layers have been fastened in contact with each other at a plurality of spaced points. Fabric layers have also been interconnected by drop stitching them together at a predetermined distance. Straps and ties extending across the outer surfaces of the fabric layers have also been used. According to another technique, the width of the monolithic structure is controlled by a system or network of cords interconnecting or linking the fabric layers. Furthermore, wires woven into the fabric layers have been used; wires of one fabric layer are linked to wires of the other fabric layer, typically by the use of a third set of wires.
It is further known to construct in situ an erosion control structure formed of a plurality of pockets between two fabric layers, by filling the pockets with sand or cementitious filler material. The fabric layers later serve to bind together the hardened pockets. Such a network or matrix of hardened forms, unlike the monolithic hardened structures mentioned above, is able to adapt to the changing contour of the earthen surface being protected, which may slowly erode or accrete from the hydraulic forces under the structure, or which may expand or contract due to ice formation. A further advantage of such a network or matrix is that hydraulic pressure above and below the structure is more readily equalized because of the numerous spaces between the hardened forms, resulting in less stress on the hardened material than in monolithic structures. Since the integrity of such a network or matrix structure depends on the integrity of the fabric interconnecting the hardened forms, which fabric is subject to deterioration and abrasion, such a structure tends to be impermanent.